In devices that transport material, such as the dye receiving material in a thermal printer, it is important to prevent scratching of the material. In a thermal printer, the scratches can remove the dyes or otherwise cause the image to be of unacceptable quality. This is especially true of transparent materials where both sides of the transparent material can be damaged by scratching. The drive means for transporting the dye receiving material through the printer, and maintaining proper registration during a printing function, must grip the material to do so. In some cases, rough surfaces are used which can cause scratches if the material is passed by them with a difference in relative velocity between the material and surface of the rough roller or drive means, during loading and unloading, for example. Hard rough rollers are preferable because they do not deflect under pinching loads, and more accurate transport is therefore achievable. Accordingly, it will be appreciated that it would be highly desirable to have a transport mechanism that uses rough surface rollers for good registration.
Other transport systems that have also been concerned with scratches include roll feed printers that would scratch only the leading edge of the roll and not the entire sheet. Sheet printers are prone to this scratch damage. For this reason, some machines do not use rough surfaces to transport and grip the material, but most of these require higher loads to accomplish the task of maintaining good control of the sheet. Accordingly, it will be appreciated that it would be highly desirable to have a transport mechanism that uses rough surface rollers for good registration but uses lower loads and prevent scratches.